In the synthesis of deoxyribonucleic acid (DNA) it is often extremely difficult to copy the entire length of single stranded ribonucleic acid (RNA) into its complementary DNA because of the highly folded nature of the RNA. In the synthesis of complementary DNA (cDNA) from messenger RNA (mRNA) for example, it is important to copy the total length of messenger RNA into DNA, otherwise the resultant gene equivalent in the form of cDNA will be incomplete. In Nature, Volume 259, No. 5543, pages 499-502, Feb. 12, 1976 there is described the isolation of a nucleic acid binding protein which is effective in unwinding the highly folded RNA so that its reverse transcription can be facilitated to yield higher quantities of DNA. This article reports the isolation of the nucleic acid binding protein from chick fibroblasts transformed by Rous sarcoma virus (RSV) and its stimulatory effect on DNA synthesis catalyzed by reverse transcriptase. As described, the binding protein is obtained using a method in which Rous sarcoma virus transformed chicken fibroblasts are sonicated, the cells are then centrifuged to remove the debris, polyethylene glycol is added in order to remove the DNA and to obtain the supernatant, the supernatant is passed through a chromagraphic column to absorb the binding protein, and lastly, the binding protein is eluted from the column with 0.2 molar salt solution.